Here "this world" is a metonym that refers to all the people in the world. Alternate translation: "Now is the time for God to judge all of the people" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here "ruler" refers to Satan. You can translate this in an active form. Alternate translation: "Now is the time when I will destroy the power of Satan, who rules this world" (See: [[rc://en/ta/man/translate/figs-activepassive]])